The processes that control binary mixing of two sizes of grains have been investigated theoretically and validated by comparison with experimental data. These seemingly simple experiments are difficult to carry out with the degree of precision needed to test the models. We have developed a methodology allowing porosity and permeability to be measured to within ± 4.415% and ± 4.989% (at a flow rate of 5.13 cm 3 /s) of each value, respectively. Theoretical considerations recognise mixing processes: (1) an interstitiation process whereby small grains fit between larger grains and (2) a replacement process whereby large grains replace smaller grains and the porosity associated with them. A major result of this work is that the theoretical models describing these two processes are independent of grain size and grain shape. The latter of these two findings infers that the models developed in this work are applicable to any shape of grain or type of packing, providing that a representative porosity of each size of grain pack is known independently, either experimentally or theoretically. Experimental validation has shown that the newly developed relationships for porosity described measurements of porosity for near-ideal binary mixtures extremely well, confirming that porosity is always reduced by binary mixing, and that the degree of reduction depends upon the size of the ratio between the two grain sizes. Calculation of permeability from the packing model has also been done. Six different permeability estimation methods have been used. It was found that the most accurate representations of the experimental permeability were obtained (1) when the exact RGPZ (Revil, Glover, Pezard, Zamora) method was used with the porosity mixing models developed in this work and (2) when the exact RGPZ method was used with the weighted geometric mean to calculate a representative grain size.

中文翻译：

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二元颗粒混合物的孔隙率和渗透率

已对控制两种尺寸晶粒的二元混合的过程进行了理论研究，并通过与实验数据的比较进行了验证。这些看似简单的实验很难以测试模型所需的精度进行。我们开发了一种方法，可以将孔隙度和渗透率分别测量到每个值的 ± 4.415% 和 ± 4.989%（流速为 5.13 cm 3 /s）内。理论考虑认识到混合过程：(1) 一种填隙过程，其中小晶粒在大晶粒之间嵌入；(2) 替换过程，其中大晶粒取代小晶粒以及与它们相关的孔隙度。这项工作的一个主要结果是描述这两个过程的理论模型与晶粒尺寸和晶粒形状无关。这两个发现中的后一个推断，这项工作中开发的模型适用于任何形状的谷物或包装类型，前提是每种尺寸的谷物包装的代表性孔隙率在实验或理论上都是独立已知的。实验验证表明，新开发的孔隙度关系非常好地描述了接近理想的二元混合物的孔隙度测量值，证实了二元混合总是会降低孔隙度，并且降低的程度取决于两者之间的比率大小颗粒大小。还根据填充模型计算了渗透率。已经使用了六种不同的渗透率估计方法。发现当精确的 RGPZ (Revil,